The present invention relates to a shear panel assembly for reducing the risk of damage to buildings as a result of lateral forces applied to the building.
Typical building frame construction includes a frame anchored to the foundation and a roof assembly supported by the frame. The frame typically includes a plurality of vertically oriented studs attached between upper and lower plates. Inner and outer siding materials are attached to the frame. In a typical residential building, framing is accomplished by employing lumber and wood products.
Lateral forces applied to the wall, which may occur as a result of high winds or earthquakes, can cause the upper section of the wall to move relative to the lower section. This movement is commonly assumed to be in a direction parallel to and in the plane of the wall. Excess movement of the upper section of the wall relative to the anchored lower section can result in damage to the frame that may be catastrophic.
A variety of designs have been developed for resisting lateral forces. One method for providing lateral stiffening includes attaching a sheet material such as oriented strand board (OSB) or plywood to the frame exterior such that it spans across several studs and is attached to the upper and lower plates. A shear force applied to the wall in a direction parallel to and in the plane of the wall is therefore transmitted through the sheet material to a bottom plate and the foundation of the structure, thereby reducing the tendency of the upper portion of the wall to move relative to the lower portion of the wall. To enhance the strength of the shear panel, the bottom plate of the shear panel is typically fastened to the foundation by a plurality of anchor bolts or tiedowns to better resist shear forces.
Shear panels that incorporate a face-mounted shear membrane must include a reduced frame member depth in order to fit within the dimensions of common or standard framing elements. The resulting panels can exhibit reduced strength, reduced resistance to lateral forces and a reduced moment of inertia. In addition, shear panels that incorporate a face-mounted shear membrane are prone to warping and torque when lateral force is applied. In particular, the application of repetitive lateral motion, such as that experienced during cyclic shear testing of prefabricated shear panels, reveals that such face-mounted membranes tend to warp and twist, leading to failure of the shear panel. Even shear panels that incorporate the shear membrane in a sandwich structure exhibit failure upon repetitive lateral movement.
Also problematic, when such panels do fail, is that they tend to exhibit a brittle failure profile, that is, the panel provides resistance to lateral movement until a failure point is reached, at which point the shear panel fails rapidly and catastrophically, with the loss of a substantial amount of structural integrity.
What is needed is a shear panel assembly with improved performance to cyclic shear loading and improved ductility so that the panel will withstand greater cyclic lateral movement, and that upon failure, fail gradually rather than catastrophically.
The present invention is directed to a shear panel assembly that includes a frame and a panel diaphragm, where the frame comprises an upper horizontal frame member, a first upright, a second upright, and a lower horizontal frame member. The frame includes a panel diaphragm edge receiving member formed on an inner peripheral face of the frame, within a depth of the frame. The panel diaphragm includes a peripheral edge that is connected to the frame at the panel diaphragm edge receiving member.
Another form the invention takes includes a shear panel that includes a frame, where the frame comprises an upper horizontal frame member, a first upright that pivotally interconnects a first end of the upper horizontal frame member, a second upright that pivotally interconnects a second end of the upper horizontal frame member, a lower horizontal frame member that pivotally interconnects a lower end of the first upright and a lower end of the second upright, and a panel diaphragm that is connected to the frame.
Yet another aspect of the invention includes a shear panel hold-down that comprises a base and at least one pivotable upright engagement tab attached to and extending from the base.
Additional objects, advantages and novel features of the invention will be set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
The advantages of the present invention will be understood more readily after a consideration of the drawings and the Detailed Description.